3,393 research outputs found
Instantiated Recoupling in Principals\u27 Enactment of Teacher Evaluations: Emotion Work and New Forms of Ceremonial Conformity in Educational Institutions
As accountability policies have proliferated and evolved in a number of organizational fields, recent scholarship in organizational sociology has paid close attention to the ways that accountability has forced tight coupling in a variety of organizations. Fewer recent studies examine efforts at ceremonial conformity that organizations may use to buffer internal practices from institutional pressures, or how organizations and their actors might attempt to engage in ceremonial conformity under newer accountability regimes. In this article, we examine how school principals enact state-mandated teacher evaluation policies with their teachers. To manage teachers\u27 stress caused by the evaluations, we find that principals often allow, and at times enable, teachers to put on a âdog and pony showâ during formal evaluations, a performance that aligns with district instructional policies but deviates from their common everyday practices. We argue that this is a novel form of ceremonial conformity that we call instantiated recoupling
Vampire Bats and Rabies: Toward an Ecological Solution to a Public Health Problem
In the first half of 2011, 21 school-age children and two adults died of rabies transmitted by the common vampire bat (Desmodus rotundus) in and around the small rural village of Yupicusa in the Peruvian Amazon (Figure 1) [1]. This is only one of many such outbreaks occurring throughout the greater Amazon Basin (Figure 2), which, despite efforts at increasing education, vaccination, and bat population control, seem to have escalated over the last three decadesâa timeline concurrent with major social and ecological changes in the area [2]. The remote and impoverished nature of communities affected by these outbreaks and the unique niche of vampire bats in a changing socioecological landscape create challenges beyond those faced in previous rabies control efforts and require new strategies to address this public health menace through ecosystem-level intervention. Here we examine this complex system and offer perspectives from a field expedition to Imaza following the 2011 outbreak
A validated measure of adherence to antibiotic prophylaxis in children with sickle cell disease
BACKGROUND: Antibiotic prophylaxis is a mainstay in sickle cell disease management. However, adherence is estimated at only 66%. This study aimed to develop and validate a Sickle Cell Antibiotic Adherence Level Evaluation (SCAALE) to promote systematic and detailed adherence evaluation.
METHODS: A 28-item questionnaire was created, covering seven adherence areas. General Adherence Ratings from the parent and one health care provider and medication possession ratios were obtained as validation measures.
RESULTS: Internal consistency was very good to excellent for the total SCAALE (α=0.89) and four of the seven subscales. Correlations between SCAALE scores and validation measures were strong for the total SCAALE and five of the seven subscales.
CONCLUSION: The SCAALE provides a detailed, quantitative, multidimensional, and global measurement of adherence and can promote clinical care and research
Minor versus major mergers: the stellar mass growth of massive galaxies from z=3 using number density selection techniques
We present a study on the stellar mass growth of the progenitors of local massive galaxies with a variety of number density selections with nâ€1Ă10â4âMpcâ3 (corresponding to M*=1011.24âMâ at z=0.3) in the redshift range 0.3<z<3.0. We select the progenitors of massive galaxies using a constant number density selection, and one which is adjusted to account for major mergers. We find that the progenitors of massive galaxies grow by a factor of 4 in total stellar mass over this redshift range. On average the stellar mass added via the processes of star formation, major and minor mergers account for 24±8, 17±15 and 34±14perâcent, respectively, of the total galaxy stellar mass at z=0.3. Therefore 51±20perâcent of the total stellar mass in massive galaxies at z=0.3 is created externally to their z=3 progenitors. We explore the implication of these results on the cold gas accretion rate and size evolution of the progenitors of most massive galaxies over the same redshift range. We find an average gas accretion rate ofâŒ66±32âMââyrâ1 over the redshift range of 1.5<z<3.0. We find that the size evolution of a galaxy sample selected this way is on average lower than the findings of other investigation
A consistent measure of the merger histories of massive galaxies using close-pair statistics I:Major mergers at z <3.5
We use a large sample of galaxies constructed by combining the
UKIDSS UDS, VIDEO/CFHT-LS, UltraVISTA/COSMOS and GAMA survey regions to probe
the major merging histories of massive galaxies ()
at . We use a method adapted from that presented in
Lopez-Sanjuan et al. (2014) using the full photometric redshift probability
distributions, to measure pair of flux-limited, stellar
mass selected galaxy samples using close-pair statistics. The pair fraction is
found to weakly evolve as with no dependence on stellar
mass. We subsequently derive major merger for galaxies at and at a constant number density of
Mpc, and find rates a factor of 2-3 smaller than previous works,
although this depends strongly on the assumed merger timescale and likelihood
of a close-pair merging. Galaxies undergo approximately 0.5 major mergers at , accruing an additional 1-4 in the
process. Major merger accretion rate densities of
yr Mpc are found for number density selected
samples, indicating that direct progenitors of local massive
() galaxies have experienced a steady supply of
stellar mass via major mergers throughout their evolution. While pair fractions
are found to agree with those predicted by the Henriques et al. (2014)
semi-analytic model, the Illustris hydrodynamical simulation fails to
quantitatively reproduce derived merger rates. Furthermore, we find major
mergers become a comparable source of stellar mass growth compared to
star-formation at , but is 10-100 times smaller than the SFR density at
higher redshifts.Comment: 26 pages, 18 figures, accepted to MNRA
Statistical properties of SGR 1900+14 bursts
We study the statistics of soft gamma repeater (SGR) bursts, using a data
base of 187 events detected with BATSE and 837 events detected with RXTE PCA,
all from SGR 1900+14 during its 1998-1999 active phase. We find that the
fluence or energy distribution of bursts is consistent with a power law of
index 1.66, over 4 orders of magnitude. This scale-free distribution resembles
the Gutenberg-Richter Law for earthquakes, and gives evidence for
self-organized criticality in SGRs. The distribution of time intervals between
successive bursts from SGR 1900+14 is consistent with a log-normal
distribution. There is no correlation between burst intensity and the waiting
times till the next burst, but there is some evidence for a correlation between
burst intensity and the time elapsed since the previous burst. We also find a
correlation between the duration and the energy of the bursts, but with
significant scatter. In all these statistical properties, SGR bursts resemble
earthquakes and solar flares more closely than they resemble any known
accretion-powered or nuclear-powered phenomena. Thus our analysis lends support
to the hypothesis that the energy source for SGR bursts is internal to the
neutron star, and plausibly magnetic.Comment: 11 pages, 4 figures, accepted for publication in ApJ
The DEEP Groth Strip Galaxy Redshift Survey. III. Redshift Catalog and Properties of Galaxies
The Deep Extragalactic Evolutionary Probe (DEEP) is a series of spectroscopic
surveys of faint galaxies, targeted at the properties and clustering of
galaxies at redshifts z ~ 1. We present the redshift catalog of the DEEP 1 GSS
pilot phase of this project, a Keck/LRIS survey in the HST/WFPC2 Groth Survey
Strip. The redshift catalog and data, including reduced spectra, are publicly
available through a Web-accessible database. The catalog contains 658 secure
galaxy redshifts with a median z=0.65, and shows large-scale structure walls to
z = 1. We find a bimodal distribution in the galaxy color-magnitude diagram
which persists to z = 1. A similar color division has been seen locally by the
SDSS and to z ~ 1 by COMBO-17. For red galaxies, we find a reddening of only
0.11 mag from z ~ 0.8 to now, about half the color evolution measured by
COMBO-17. We measure structural properties of the galaxies from the HST
imaging, and find that the color division corresponds generally to a structural
division. Most red galaxies, ~ 75%, are centrally concentrated, with a red
bulge or spheroid, while blue galaxies usually have exponential profiles.
However, there are two subclasses of red galaxies that are not bulge-dominated:
edge-on disks and a second category which we term diffuse red galaxies
(DIFRGs). The distant edge-on disks are similar in appearance and frequency to
those at low redshift, but analogs of DIFRGs are rare among local red galaxies.
DIFRGs have significant emission lines, indicating that they are reddened
mainly by dust rather than age. The DIFRGs in our sample are all at z>0.64,
suggesting that DIFRGs are more prevalent at high redshifts; they may be
related to the dusty or irregular extremely red objects (EROs) beyond z>1.2
that have been found in deep K-selected surveys. (abridged)Comment: ApJ in press. 24 pages, 17 figures (12 color). The DEEP public
database is available at http://saci.ucolick.org
The evolution of galaxies at constant number density: a less biased view of star formation, quenching, and structural formation
Due to significant galaxy contamination and impurity in stellar mass selected samples (up to 95 per cent from z = 0â3), we examine the star formation history, quenching time-scales, and structural evolution of galaxies using a constant number density selection with data from the United Kingdom Infra-Red Deep Sky Survey Ultra-Deep Survey field. Using this methodology, we investigate the evolution of galaxies at a variety of number densities from z= 0â3. We find that samples chosen at number densities ranging from 3 Ă 10â4 to 10â5 galaxies Mpcâ3 (corresponding to z ⌠0.5 stellar masses of Mâ = 1010.95â11.6 M0) have a star-forming blue fraction of âŒ50 per cent at z ⌠2.5, which evolves to a nearly 100 per cent quenched red and dead population by z ⌠1. We also see evidence for number density downsizing, such that the galaxies selected at the lowest densities (highest masses) become a homogeneous red population before those at higher number densities. Examining the evolution of the colours for these systems furthermore shows that the formation redshift of galaxies selected at these number densities is zform > 3. The structural evolution through size and SÂŽersic index fits reveal that while there remains evolution in terms of galaxies becoming larger and more concentrated in stellar mass at lower redshifts, the magnitude of the change is significantly smaller than for a mass-selected sample. We also find that changes in size and structure continues at z < 1, and is coupled strongly to passivity evolution.We conclude that galaxy structure is driving the quenching of galaxies, such that galaxies become concentrated before they become passive
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